Fatty liver can be accompanied by hepatic inflammation to cause liver cirrhosis. Even non-alcohol drinkers can suffer from a symptom analogous to an alcoholic steatohepatitis. The symptom is referred to as a nonalcoholic steatohepatitis (NASH), and has attracted attention as a new life-style related disease as well as high blood pressure, diabetes, hyperlipemia.
With increase in the numbers of obese people and patients suffering from life-style related diseases due to the shift to western-style diets such as lipid-rich diets, and lack of physical activity, the numbers of fatty liver patient and NASH patient presumably increase. Hence, it is necessary to develop new medicines for NASH treatment, suppressants for suppressing NASH development, and/or functional foods for reducing risk of NASH occurrence and NASH development, and establish methods of curing NASH and preventing NASH development.
Human NASH is diagnosed by identification of biochemical and histopathological characters of human blood. NASH pathological animal model can be prepared from rats with a partial pressure of oxygen in rat blood being kept at a low level, for evaluation of unknown functional materials.
Non-patent reference 1 (Takayama F. et al: J. Pharmacological Sci., 100 (1), pp.164 (2006).) describes in detail a relationship between the NASH pathological animal model and an oxidative stress. In this reference, the NASH pathological rat model promotes hydroxide radical production at its liver mitochondria, suggesting that it is possible to prevent, alleviate, and cure NASH by promoting hydroxyl radical scavenging activity at its liver mitochondria.
Generally, active oxygen species (ROS) is widely known as an origin of diseases, for example life-style related diseases such as cancer, cataract, nerve disease, kidney disease, allergy, and diabetes. In general, the ROS involving diseases are effectively suppressed by antioxidants.
Non-patent reference 1 shows an experiment using NASH pathological rat model prepared similarly to NASH pathological human model in which liver mitochondria promotes active oxygen radical production, strongly suggesting a relationship between oxidative stress and NASH.
As containing phycocyanin as an effective ingredient, the dried spirulina (e.g., Spirulina platensis) powder has been consumed as a supplement, and can be widely utilized as ingredients of cosmetic and medical products or the like, as described in patent reference 1 (Japanese unexamined patent application publication No. 2007-215507), patent reference 2 (Japanese unexamined patent application publication No. 2004-238519) and patent reference 3 (Japanese unexamined patent application publication No. 2004-256478).
The health functionality of dried spirulina can be attributed to its activities for scavenging ROS, especially lipid-peroxidate (see non-patent reference 2; Vadiraja B. Bhat and K. M. Madyastha: Biochem. Biophys. Res. Commum., 275, pp. 20-25 (2000).), hydroxyl radical (see non-patent reference 3; Pinero Estrada et al: II Farmaco., 56, pp. 497-500 (2001).), peroxynitrite (see non-patent reference 4; Vadiraja B. Bhat and K. M. Madyastha: Biochem. Biophys. Res. Commum., 285, pp.262-266 (2001).), and so on.
The dried spirulina product is known as an ingredient effective in preventing and curing various diseases. For example, the dried spirulina product can bring various effects such as blood cholesterol suppression effect (non-patent reference 5; Toshimitsu Kato et al., Publication of Japanese Society of Nutrition and Food Science 37(4), 323-332 (1984).), hyperlipidemia alleviation effect (non-patent reference 6; Kazuko Iwata et al., Publication of Japanese Society of Nutrition and Food Science 40 (6), 463-467 (1987).), blood pressure regulation effect (non-patent reference 7; Kazuko Iwata et al., Kagawa Education Institute of Nutrition abstract, 21, 63-70 (1990).). The dried spirulina product can have a UV absorption effect for being applied to skin care medicine (see patent reference 2), as well as immune system enhancement effect and allergic inflammation suppression effect (see non-patent reference 8; Hayashi O. at al., J. Nutr. Sci. Vitaminol., 44, 841-851 (1998) and patent reference 3).
The application of the dried spirulina products to foods and pigments have been proposed as described below, and partially achieved for practical use. The dried spirulina product can be applied to foods (see patent reference 1 and patent reference 4 (Japanese unexamined patent application publication No. 1995-289201). Phycocyanin extracted from the dried spirulina product can be available as a food pigment, as proposed in patent reference 5 (Japanese unexamined patent application publication No. 2001-190244) and patent reference 6 (Japanese unexamined patent application publication No. 2006-230272).
Although the dried spirulina product has a high health functionality, radical scavenging active level of the dried spirulina product for utilizing the functionality has not been determined yet. Besides, the application of dried spirulina product has not been established yet, as to specific use of fermentation products for treatment of life-style related diseases involving active oxygen species.
In view of this circumstance, it is necessary to meet increasing demand for establishment of methods for applying the highly radical-scavenging active dried spirulina products to treatment of life style-related diseases, especially hepatic inflammation such as NASH.